Wildfire's worst may not be over for California, Carson

In this undated photo provided by the U.S. Forest Service, the Rim Fire burns near Yosemite National Park, Calif. The wildfire outside Yosemite National Park  one of more than 50 major brush blazes burning across the western U.S.  more than tripled in size overnight and still threatens about 2,500 homes, hotels and camp buildings. Fire officials said the blaze burning in remote, steep terrain had grown to more than 84 square miles and was only 2 percent contained on Thursday, down from 5 percent a day earlier. (AP Photo/U.S. Forest Service)

Hazy smoke from a wildfire more than 150 miles away near Yosemite National Park descended Thursday, Aug. 22, 2013, on Reno and the downtown casino district. Washoe County Health District officials issued an air quality alert because the Air Quality Index worsened to the unhealthy zone for sensitive groups, including the elderly and young children. (AP Photo/Scott Sonner)

In this undated photo provided by the U.S. Forest Service, the Rim Fire burns near Groveland Ranger Station in Groveland, Calif. The wildfire outside Yosemite National Park  one of more than 50 major brush blazes burning across the western U.S.  more than tripled in size overnight and still threatens about 2,500 homes, hotels and camp buildings. Fire officials said the blaze burning in remote, steep terrain had grown to more than 84 square miles and was only 2 percent contained on Thursday, down from 5 percent a day earlier. (AP Photo/U.S. Forest Service)

Shawn Woottenn and other members of the Lathrop-Manteca fire department wait in the town of Tuolumne, Calif, Friday Aug. 23, 2013. The town is under advisory evacuation as the Rim Fire grows in size.(AP Photo/The Modesto Bee, Andy Alfaro) NO SALES, NO MGS, NO TV, ONLINE AP MEMBERS ONLY

Firefighters wait in the town of Tuolumne, Calif, Friday Aug. 23, 2013. The town is under advisory evacuation as the Rim Fire grows in size.(AP Photo/The Modesto Bee, Andy Alfaro) NO SALES, NO MGS, NO TV, ONLINE AP MEMBERS ONLY

Kayla Stanton, right, and Preston Holley, left, pack up belongings for friends as the Rim Fire threatens the small town of Tuolumne, Calif, Friday Aug. 23, 2013. (AP Photo/The Modesto Bee, Andy Alfaro) NO SALES, NO MGS, NO TV, ONLINE AP MEMBERS ONLY

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Carson City remained in a smoky haze Saturday, with an air quality rating of “unhealthy” listed at AirNow.com.

Wind continues to blow smoke from the Rim fire directly toward Carson City, said Marvin Boyd, a meteorologist with the National Weather Service in Reno. He added that the American fire near Foresthill, Calif., also continues to send smoke this way.

“There’s no significant change in the wind directions until next weekend,” he said Saturday. “It’s not looking too good right now for relief.”

That’s bad news for this region; it’s much worse for the Yosemite National Park area. As the Rim fire raged along the park’s remote northwest edge Saturday, officials cleared brush and set sprinklers to protect two groves of giant sequoias.

The iconic trees can resist fire, but dry conditions and heavy brush are forcing park officials to take extra precautions in the Tuolumne and Merced groves. About three dozen of the giant trees are affected.

“All of the plants and trees in Yosemite are important, but the giant sequoias are incredibly important both for what they are and as symbols of the National Park System,” said spokesman Scott Gediman.

The trees grow naturally only on the western slopes of the Sierra Nevada and are among the largest and oldest living things on earth.

The Tuolumne and Merced groves in are in the north end of the park near Crane Flat. While the Rim fire is still some distance away, park employees and trail crews are not taking any chances.

“We’re not looking at them as any kind of immediate threat, but we’re taking precautions,” Gediman said.

More than 5,500 homes are threatened, and four have been destroyed. Voluntary and mandatory evacuations have been ordered.

The fire has been burning for a week. The cause is under investigation.

The fire held steady overnight at nearly 200 square miles along the park’s northern border, but a spokesman for the California Department of Forestry and Fire Protection said firefighters didn’t get their usual reprieve from lower early-morning temperatures Saturday.

“This morning we are starting to see fire activity pick up earlier than it has the last several days,” said Cal Fire spokesman Daniel Berlant. “Typically, it doesn’t really heat up until early afternoon. We could continue to see this fire burn very rapidly today.”

The Rim fire started in a remote canyon of the Stanislaus National Forest a week ago and is just 5 percent contained.

The fire has grown so large and is burning dry timber and brush with such ferocity that it has created its own weather pattern, making it difficult to predict in which direction it will move.

“As the smoke column builds up it breaks down and collapses inside of itself, sending downdrafts and gusts that can go in any direction,” Berlant said. “There’s a lot of potential for this one to continue to grow.”

The tourist mecca of Yosemite Valley, the part of the park known around the world for such sights as the Half Dome and El Capitan rock formations and waterfalls, remained open, clear of smoke and free from other signs of the fire that remained about 20 miles away.

More than 2,600 firefighters and a half-dozen aircraft are battling the blaze.

The fire is burning toward the Hetch Hetchy reservoir, where San Francisco gets 85 percent of its water and power for municipal buildings, the international airport and San Francisco General Hospital. Gov. Jerry Brown declared a state of emergency because of the threats.

Officials with the San Francisco Public Utilities Commission are running continuous tests on water quality in the reservoir that is the source of the city’s famously pure water.

Deputy General Manager Michael Carlin told The Associated Press on Saturday that no problems from falling ash have been detected.

“We’ve had other fires in the watershed and have procedures in place,” he said.

The commission also shut two hydro-electric stations fed by water from the reservoir and cut power to more than 12 miles of lines. The city has been buying power on the open market.

A 4-mile stretch of State Route 120, one of three entrances into Yosemite on the west side, remains closed. Two other western routes and an eastern route were open.